The NASA EV-2 Cyclone Global Navigation Satellite System (CYGNSS) Mission

Transcription

1 International Ocean Vector Wind Science Team Meeting Kailua-Kona, Hawaii USA 6-8 May 2013 The NASA EV-2 Cyclone Global Navigation Satellite System (CYGNSS) Mission Chris Ruf (1) (CYGNSS Principal Investigator), Scott Gleason (2), Zorana Jelenak (3), Stephen Katzberg (4), Aaron Ridley (1) Randall Rose (5), John Scherrer (5) and Valery Zavorotny (6) (1) University of Michigan; (2) Concordia University; (3) NOAA/NESDIS; (4) NASA LaRC; (5) Southwest Research Institute; (6) NOAA ESRL For more information:

2 CYGNSS Team University of Michigan Chris Ruf (PI), Derek Posselt (Deputy PI), Aaron Ridley (Instrument Scientist) Damen Provost (UM Project Mgr), Linda Chadwick (UM Business Mgr), Bruce Block (UM Technical Mgr) Southwest Research Institute John Scherrer (Project Mgr), Randy Rose (Systems Eng), John Eterno (Spacecraft), Debbie Rose (Mission Ops) Surrey Satellite Technology US Brian Johnson (DDMI) NASA Ames Research Center James Chartres (Deployment Module) Science Team Bob Atlas, NOAA; Paul Chang, NOAA; Maria Paola Clarizia (UM/NOC); James Garrison, Purdue U; Scott Gleason, Concordia U; Joel Johnson, Ohio State U; Stephen Katzberg, NASA LaRC (retired); Sharan Majumdar, U-Miami; Perry Samson, UM; Donald Walter, S. Carolina State U; Valery Zavorotny, NOAA; Zorana Jelenak, NOAA 2

3 CYGNSS Schedule 3 3

4 CYGNSS Science Goals & Objectives CYGNSS Science Goal Understand the coupling between ocean surface properties, moist atmospheric thermodynamics, radiation, and convective dynamics in the inner core of a tropical cyclone (TC) CYGNSS Objectives Measure ocean surface wind speed in all precipitating conditions, including those experienced in the TC eyewall Measure ocean surface wind speed in the TC inner core with sufficient frequency to resolve genesis and rapid intensification Limitations of current spaceborne ocean surface wind sensors Traditional satellite remote sensing channels for ocean surface winds are significantly attenuated by intense precipitation Traditional LEO polar orbiters have revisit times that are infrequent relative to time scale of rapid intensification phase of TC development CYGNSS Uses a new measurement technique and a new satellite mission architecture 4

5 GNSS-R Bistatic Radar Quasi-Specular Surface Scattering GPS direct signal provides reference Forward scattered signal contains surface info Scattering cross-section image measured by UK-DMC-1 spaceborne mission with variable lag correlation and Doppler shift 5

6 Performance in Intense Precipitation One-way transmissivity through typical tropical storm (5 km freezing level) for: GPS (1.575 GHz), ASCAT (5.255 GHz), QSCAT (13.4 GHz) Airborne GNSS wind speed retrieval during overpass of Hurricane Bill on 19 Aug Strong rain bands (black) do not noticably affect the GNSS retrieved wind (red) 6

7 GNSS Scientific Measurements Science Objective Measure ocean surface winds under TC conditions Precip Scientific Measurement Estimated Performance Observable Windspeed uncertainty Spatial resolution Physical Parameter < 100 mm/hr (25 km footprint) Greater of 2 m/s or 10% of windspeed Variable km (ground processing) Windspeed dynamic range < 70 m/s (Cat 5) Measure ocean surface winds in TC inner core with high temporal frequency Mean revisit time Earth coverage 4 hr > 70% coverage of all historical TC storm tracks 7

8 CYGNSS Constellation 8

9 CYGNSS End-to-End Simulator Software model of all critical steps in the wind speed retrieval process: Dynamic orbit propagators for GPS and CYGNSS constellations Signal generation by GPS transmitter satellites Free space propagation to the specular reflection point on the Earth surface Bi-static forward scattering from the wind driven, roughened ocean surface Receive antenna gain pattern projected onto the Earth surface Link budget for received signal strength Fading and thermal noise statistics of received signal Accuracy, precision and resolution of Delay Doppler Map data product Wind speed retrieval algorithm 9

10 Deriving Coverage Mask (left) One of 2 nadir antenna patterns projected onto Earth (altitude 500 km, 60 o rotation, 28 o tilt) (center) SNR of received signal (10 m/s WS, 45 o inc. angle) (right) +8 db SNR contour with both antennas (meets WS retrieval uncertainty requirement) 10

11 90 min (one orbit) coverage showing all specular reflection contacts by each of 8 s/c 24 hr coverage provides nearly gap free spatial sampling within +/- 35 deg orbit inclination CYGNSS Earth Coverage 11

12 CYGNSS Historical Storm Track Overlay 12

13 CYGNSS Revisit Time Requirement is 12 hr mean revisit Probability distribution of revisit time for all Earth samples within +/-35 o (solid) and for samples of historical storm tracks (dashed). Revisit stats derived from PDF demonstrate 4 hr mean storm revisit and ~9 hr to revisit 90% of all storms 13

14 Hurricane Overpass Case Study Time lapse simulation comparing CYGNSS and ASCAT coverage of Hurricane Frances just before landfall Snapshots of all samples taken in 3 hour intervals Hurricane inner core shown as large blue dot 14

15 CYGNSS Observatory (exploded view) 15

16 CYGNSS Observatory (1 of 8) Observatory Power: 48.8 W (EOL margin 30.3%) Comm: 1.25 Mbps S-Band (31% link margin) Mass: 17.6 kg Orbit Altitude: 500 km Inclination: 35 deg Launch 6 Oct

17 Complete Flight Segment with Deployment Module 17

18 For more information: 18